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Environmental impact assessments of industrial processes are based on
the amount of raw materials, residues and energy in the production of
commodities. A materials flow analysis of these amounts and an
environmental impact analysis are usually the first steps in a product
life cycle assessment. In the extraction of mineral resources, these
various amounts say a great deal about the environmental impact of a
process: for example, for the production of one tonne of aluminium
about 5 t of ore and 3 t of rock are mined and transported, and about
16,000 kWh/t electrical energy are used. These analyses reveal the
situation for the production of a specific mineral commodity but they
also provide an indication of where it is possible to improve the
process efficiency.
The enormous diversity of mineral deposits, characterised by various
parameters, including geometry, size, depth, mineral composition and
grade, together with the numerous extraction and processing methods,
results in very different mass flow diagrams for different deposits
using different extraction and processing methods. It is usually risky
to draw general conclusions about the materials flow for a natural
resource on the basis of data for one or only a few known deposits and
the processes involved.
Given (a) the importance of mineral commodities in supplying the needs
of humankind, (b) the importance of mineral extraction for industrial
processes, (c) the need to protect our environment, and (d) the fact
that these resources are all limited to one extent or the other, there
is also an enormous need to establish a reliable and objective
database as the basis for further analyses.